<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>固定帧动画</title>
    <style>

        .bird {
            position: absolute;
            left: 100px;
            top: 100px;
            width: 86px;
            height: 60px;
            zoom: 0.5;
            background-repeat: no-repeat;
            background-image: url(https://p.ssl.qhimg.com/t01f265b6b6479fffc4.png);
            background-position: -178px -2px;
            animation: flappy 0.5s step-end infinite;
        }
        @keyframes flappy {
            0% { background-position: -178px -2px;}
            33% { background-position: -90px -2px;}
            66% { background-position: -2px -2px;}
        }
    </style>
</head>
<body>
    <div class="bird"></div>
</body>
</html>